Communication booth



April 2, 1946. R, L. 'HoYLE COMMUNICATION BOOTH Filed Feb; lo, 1945 Patented Apr. 2, 1946 UNITED 'STATES PATENT: ortica'A COMMUNICATION BOOTH Robert L. Hoyle, Chicago, Ill., assigner, by mesne assignments, to Burgess-Manning Company, Chicago, Ill., a corporation of Illinois Application February 10, 1943, Serial No. 475,331

(Cl. 2li-3.5)

13 Claims.

This invention relates to improvements in communication Ibooths of the type which is adapted for use in noisy surroundings, and which pro'- vides a quiet zone within the booth where communiation can be carried on, over the telephone or between two persons standing in the booth. In particular, the invention relates to that type of communication booth in which the quiet zone of communication is obtained by means of a sound-absorbing construction applied to the interior surfacesof the walls and acoustically exposed to the space within the booth, whereby sound energy within the booth is absorbed. 'Ihe invention is of especial value with that type of booth in which the interior is not completely enclosed by the walls, but in which the entrance, or

other portion of the'walls, is permanently open, whereby the space within the 'booth is in direct communication with the space outside the booth. A communication booth of this type is described in Weiss Patent 2,141,117, granted December20, 1938. The invention may also be used with a booth in which the. interior vis totally enclosed by the walls and a door.

In thebooths of this general type known heretofore the walls are of imperforate sheet material, and a thick layer of porous sound-absorbing ma- .terial isarranged as a lining against the interior surfaces of the walls.

If desired, a Vfacing of foraminous sheet material may be arranged to cover the layer of sound-absorbing material and presentan attractive surface for the interior of the booth. Asis known, such a foraminous facing is substantially transparent to sound and does not affect appreciably the properties of the porous materialffor absorbing the sound energy `which is present within the booth.

range,'which, for the average person. is 20 cycles per second, are sometimes present and such energy is also augmented in the booths known heretofore with the result that a throbbing sensation is sometimes experienced which is quite disturbing.

It is the object ofthe present invention to prol vide an improved communication booth of the character described which is freeof the descrlb'ed objection and within which the low frequency sound, as well as the high frequency sound, is at such low intensity that it does not interfere with the reception and transmissionof messages within the booth, or have a Vdisturbing effect upon the user.

'I'here is no sharp line of demarcation between the high frequency sound which is quieted effectively and the low frequency sound which is auel mented in the booths known heretofore. but there israther a gradualI transition from one effect to the other. At 250 cycles per second there is a definite quieting and below 150 cycles per second there is a definite augmentation of the sound within narrow bands of frequencies. The range varies somewhat with booths having different dimensionsl The transition point, or cut-oil! frequency, is between these two points, and, for purposes of definition, may be considered to be at approximately 200 cycles per second. Where high frequencies and low frequencies are referred to herein, frequencies above and below this cut-oli',

respectively, are contemplated. the latter term including the frequencies below the' audible range mentioned heretofore. f

Briefly,-the improved. quietness in the low frequency sound range is obtained b'y Providinga multiplicity of small openings in the wall'members of the booth located exteriorly of the sound A communication booth of the type described, in

general, has excellent quieting properties. vHowever, it has been found that where the sound in the surrounding space includes substantial amounts in the low frequency range. such low Atmospheric frequencies below the lower limit oi? the audible 55 absorbing material, and regulating the quantity and arrangement of the openings so as to be4 within critical limi-ts which are specified hereinafter.

In the drawing: Fig. 1 is a perspective view of a communication booth made in accordance vention: and

Fig. 2 is a fractional sectional view of a wall of vthe booth.

The booth is enclosed upon the rear Ill. the two sides II and the top I 2. The front is Dermanently open, whereby the spacel within the booth is in direct communicationwiththe space outside the booth. The walls are supported upon spaced-apart supports I l, thereby providing spaces i4 between the supports. which spaces also provide direct communication between the space within the b'ooth and that outside the booth. lThe `with the present in- -the rigidityof the wall structure.

b'ooth is suiciently high to accomodate a person standing up, and is usually deeper from front to back than it is widebecause such an arrangement provides the best* quieting results. In a specific example, the inside dimensions of the booth were as follows: height 6 feet 5 inches, depth 3 feet and width 2 feet.

A shelf I5 may be provided at the rear of the booth and a telephone instrument I6 may be installed upon the shelf, the shelf being at a convenient height for a person using the telephone while standing, A` lighting fixture l1 may be provided in the rearward portion of the top of the booth.

In Fig, 2 is illustrated a transverse section of a wall which gives the booth the desired acoustic properties. Usually all Walls of the booth are of this construction, The wall consists of the per- Wall member I9 may be of various thicknesses.`

Sheet metal having a thickness of 0.01 inch and plywood having a thickness of 3A inchk may be used satisfactorily. The layer of sound absorbing material may also be of various thicknesses,

` 4and in a specific example was 3 inches thick. It

may be composed of any of the well known soundv absorbing materials, such as porous mineral wool or a similar porous blanket of vegetable fibers, animal hair, or the like. The interior facing member 2| may be composed of thin foraminous sheet material, such as perforated metal, plywood, hard pressed fibrous material, phenol-formaldehyde resin, andthe like. As has been'stated heretofore, the facing 2| is sound transparent, andthe sound-absorbing material is acoustically exposed to the space within the booth in the same manner as if it were .directly exposed to said space.

If desired, bracing members 22 may be arranged between wall member I9 and facing 2| to increase may be in the form of strips of a width equal to the distance between wall member I9 and facing 2| and may be arranged in the form of a grid of intersecting strips.v 'Bracing members of this character are especially desirable where the wall member I9 and facing 2| are composed of thin, flexible sheet material, such as thin plywood.

In accordance with the present invention wall member I9 is provided with small openings 23 disinch in diameter.

Members 22 With walls of ainch plywood and openings inch in diameter and spaced approximately 3 inches apart between centers. a substantially lower level of low frequency sound is obtained over` that present in a similar booth having imperforate exterior wall members. The improved quietness is quite noticeable and renders the booth more :satisfactory for use.

aggregate area of the openings is ,equal to ap- In such arrangement the ber.

f' wall area.

proximately 0.075% of the area of the wall mem- With openings having a diameter greater than @3f inch a spacingv of approximately 3 inches between the centers of adjacent openings produces a closely similar level of low frequency sound. In order to produce a lower level of low frequency sound the size of the imperforate sections between adjacent openings may not exceed a .definite limit, andthis limit is approximately the same for openings of diferentsize. If the imperforate sections are large, they exhibit properties similar to those of an imperforate wall member and, in proportion to their size, detract from the beneficial .effect which is the object of the invention. To provide a lowered level of low use of the booth, the average spacing between the centers of adjacent openings should not exceed approximately 3 inches.

The openings 2| should be distributed substantially uniformly over the area of the wall member, as is evident from the foregoing description. By this it is not meant that the size and spacing of the openings must be quite uniform. Decora,- tive and other non-uniform patterns may be employed as long as large imperforate areas are not thereby formed.

With wall members of the same material and 3% inch diameter openings, a progressively lower level of low frequency sound is obtained as the openings are spaced more closely together than 3.0 inches until a spacing of 3A, inch between centers is reached. This conforms to an aggregate area of openings equal to approximately 1.0% of the With closer Aspacing than this the sound level remains substantially the same, but when a spacing of 1A; inch is employed, which conforms to an aggregate'area of openings equal to approximately l3.0% of the wall area, the level of the highfrequency sound becomesnoticeably higher, and an open area of more than approximately 3.0% `of the wall area is not satisfactory because of the higher level of high frequency sound. The same, in general, istrue with openings having a diameter of 1A inch, and with such openings the aggregate area of the openings should not exceed approximately 3.0% of the wall area. Openings having a diameter substantially greater than 1A; inch are not suitable for use. When openings lof such size are spaced suiiiciently close together to produce a substantially valso impinges on the exterior surfaces of the exterior. wall members and sets them in vibration. Within the low frequency range, there are narrow bands of frequencies Within which the exterior wall members respond very readily and considerable sound of' such frequencyl is transmitted to the interior of the booth .by the diaphragmatic action of the exterior Wall members. The sound-absorbing construction comprising the thick layer of sound-absorbing material and the foraminous interior facingmemb er is effective in absorbing the high frequency sound, but not the low frequency sound. 'I'he high Vfrequency sound, therefore, both that entering through the open entrance and that due to the vibration of the' lmperforate exterior wall member, is'absorbed andvquieted. 'I'he low frequency sound entering through the open entrance passes through the sound-absorbing conmatter of experience that the intensity of lov.'`

frequency sound is greater within the booth than it is in the surrounding space. y

In the construction of the present invention,

vv the foraminous wall member I9, with the aggregate area and spacing of the openings limited as described heretofore, is pervious, or transparent, to low frequency sound, but' is substantially impervious or opaque to high frequency sound.y

of the open entrance and the open spaces at the' bottom passes through the sound-absorbing material, and is not reflected by the-wall members I9, 'but passes through said wall members into the space surrounding the booth. Similarly, the low cupying from approximately 0.075% to be approximately 3.0% of the area of said exterior wall y memberand not exceeding in size the approxifrequency sound in the surrounding space may' pass into the-booth through the Wall member I9 and the sound-absorbing material, a small amount of its energy being dissipated Within said material. In this way, the intensity of low frequency sound within the booth is slightly less than that outside the booth. Experience has shown that this intensity is not sufficient to cause interference or disturbance to the user of the booth.

If the aggregate area of the openings is greater than approximately 3.0% of the wall area or the openings are spaced less than 1/2 inch between centers, the Wall members I9 are pervious to high frequency sound and suiiicient of such sound passes through the said wall members and through the porous material 20 to increase the level of high frequency sound in the booth.

Theinvention is not limited to a communication booth having an open entrance Aor open spaces in the Walls. totally enclosed booth having a door. In such case al1 of the sound which enters the booth is transmitted by the door, or passes through the walls,l as explained heretofore. Theaction by which quietness is obtained is similar to that which has been described.

1. A communication booth comprising a composite wall enclosing a zone of communication Within said booth. said composite wail comprising an exterior wall member and a sound-absorbing construction arranged adjacent the interior .surface of said exterior wall member and acoustically exposed to the space within saidbooth. said exterior wall member having a multiplicity Vof openings therein distributed substantially uniformly over the area thereof, said openings voc- It may be used with a` mateequivalent` of a circular opening having a' f diameter of 1/4. inch.

terior surface of said exterior wall member and acoustically exposed to the space within said booth, said exterior wall member having a multiplicity of openings therein distributed over the'area thereof, said openings occupying from approximately 0.075% to approximately 3.0%

-of the area of said exterior Wall member, adja-l cent openings being spaced apart on an average from approximately 1/2 inch to approximately 3 inches between centers.

3. A communication booth comprising a composite Wall enclosing .a zone of communication within said booth, the wall being omitted from a' portion of the sides of said booth wherebythe space within said booth is in direct communication with the space outside said booth, said composite wall comprising an exterior Wall member and a sound-absorbing construction arranged adjacent the interior surface of said exterior wall member and acoustically exposed to the space within said booth, said exterior wall member having openings therein distributed substantially uniformly over the area thereof, saidopenings occupying from approximately 0.075% to approximately 3.0% of the area of said exterior wall member and not exceeding in size the approximate equivalent of a circular opening 1/4 inch in diameter, adjacent openings being spaced apart on an average from approximately 1/2 inch to approximately 3 inches between-centers.

`4. A communication booth comprising a composite wall enclosing a zone of communication within said booth, the walls being omitted from a portion of the sides of said booth whereby the space within said booth is in direct communication with the space outside said booth, said composite wall comprising an exterior wall member and a layer of porous sound-absorbing material lining the interior surface oi' said exterior wall memberand acoustically exposed to the space within said booth, said exterior Wall member having openings therein distributedover the area of said exterior wall member, said openings occupying from approximately 0.075% 4to approximately 3.0% of said area, the average spacing between .the centers of adjacent openings-'being between posite wall comprising an exterior wall member i and a sound-absorbing construction lining the interior surface of said exterior wall member and acoustically exposed to the space within said booth, said exterior wall member having openings therein distributed substantialiy uniformly over the area thereof, said openings occupying approximately 1.0%l of the area of said exterior wall member and not exceeding in size the approximate equivalent oi' a circular opening V4 inchindiameter.l

6. -A communication booth comprising a composite wall forming an enclosure, the wall being omitted from a portion of the sides of said booth whereby the interior of said booth is in direct communication with the exterior of said booth, said composite wall comprising an exterior lwall member and a sound-absorbing construction arranged adjacent the interior surface of said exterior wall member and acoustically exposed to the space within said booth, said exterior wail member having a multiplicity of openings distributed over the area thereof, said openings being approximately e inch in diamete'rand spaced Aapart from approximately M; inch to approximately 3.0 inches between centers.

'7. A communication booth comprising a composite wall enclosing a zone ofcommunication within said booth, said composite wall comprising an exterior wall member and a sound-absorbing construction arranged adjacent the interior surface of said exterior wall member and acoustically exposed to the space within said booth, said exterior Wall member having a multiplicity of Aopenings therein, said openings being in size the approximate equivalent of circular openings having a diameter of from approximately 0.02 inch to approximately A inch, the average spacing between the centers of adjacent openings being between approximately l/2 inch and approximately 3 inches.

8, A communication booth comprising top, rear.

.tributed over the area thereof, said openings occupying from approximately 0.075%. to approxposite wall enclosingy a zonev of,communication within said booth, said composite wall comprising a sheet-form'exterior wall member, said exterior wall member being foraminous, the effective aggregate area of the foramina extending through said exterior wall' member being from approximately 0.075% to approximately 3.0% of the area of said exterior wall member, and a sound-absorbing construction arranged adjacent the interior surface of said exterior wall member and acoustically exposed to the space within said booth.

11. 'A communication vbooth comprising a composite wall enclosing a zone of communication upon at least three sides 'and the top thereof, said composite wall comprising a sheet-form exterior wall member, said exterior -wall member having imately 3.0% of the area of said exterior wall I' member 'and not exceeding in size the approximate equivalent of circular openings 1A inch in diameter, the average spacing between the centers of adjacent openings beingbetween approximately l/ inch and approximately 3 inches.

9. A communication booth comprising substantially vertical walls and a top wall, said vertical walls being mounted upon spaced-apart supports, the spaces between said supports providing 01, said openings occupying from approximately 0.075% to approximately 3.0% of the area of said exterior wall lmember and-not' exceeding in size the approximate equivalent of circular openings A inch in diameter, the average spacing between the centers of adjacent openings not exceeding approximately 3 inches.

within said booth, the wall being omittedr froma 65 10. A communication booth comprising a comopenings therein distributed over the area thereof,V said openings occupying from vapproximately 0.075% -t approximately 3.0% of the area 0f said exterior wall member and not exceeding in size ,the approximate' equivalent of circular opening 1/4 inch in diameter, the average spacing between the centers of adjacent openings not exceeding approximately 3 inches, and a sound-absorbing construction lining the interior surface of said exterior wall member and acoustically exposed to the space within said booth.

12. A communication booth comprising a composite wall enclosing a zone of communication within said booth, said composite wall comprising an exterior Wall member and a sound absorbing construction arranged adjacent to the interior surface of said exterior wall member and acoustically exposed to the space within said booth, said exterior wall member having a-.multiplicity of openings therein distributed over the area thereof, said openings occupying from approximately 0.075% vto approximately 3.0% of the area of said exterior wall member and not exceeding in size the approximate equivalent of a circular opening having a diameter of A inch, the average spacing between thecenters of adjacent openings being from approximately inch to approximately 3 inches. i I

13. A communication booth comprising a 4mposite wall enclosing .a zone of communication Portion of the sides of said booth whereby the space within said booth is in direct communication with the space outside said booth, said composite wall comprising an exterior wall 4member and a sound absorbing construction arranged mately 3.0% of the area of said exterior wall member and not exceeding in size the approximate equivalent of a circular opening having 'a jA diameter of 1A inch, the average spacing vbetween the centers of adjacent openings being from approximately 1/2 inch to approximately 3 inches.

ROBERT L. HOYLE. 

